The source of circulating male hormones in elderly subjects with and without prostate hyperplasia (BPH) will be studied. Testosterone, dihydrostestosterone (DHT) and 3alpha androstanediol (3alpha-diol) kinetics will be studied and values compared with those of younger men. This study involves RIA of T, DHT, and 3alpha diol in blood as well as determination of metabolic clearance, production, and interconversion rates (transfer constants). This study should elucidate whether the elevated levels of DHT, reported by us and now confirmed by others, arises from increased peripheral conversion and/or direct secretion. In a separate project we plan to determine the relative role of splanchnic and extrasplanchnic site of DHT. This will require a collaborative effort with the cardiac catheterization team since hepatic and peripheral blood samples will have to be obtained. BIBLIOGRAPHIC REFERENCES: Horton, R., Steroid Dynamics in Physiology of Endocrinology, Ed. L. DeGroot (in press), 1977. Horton, R., Androgen Hormones and Prehormones in Young and Elderly Men, NIH Symposium on Benign Prostate Hyperplasia, US Govt Printing Office 76-113, 1976 (in press).